TROLIE (Transmission Ratings and Operating Limits Information Exchange) is an open-source LF Energy project, hosted under LF Projects, that defines an OpenAPI-based REST specification for exchanging transmission facility ratings and operating limits. It responds to FERC Order 881, which requires North American Transmission Owners, Transmission Operators, Transmission Providers and Reliability Coordinators to exchange ambient-adjusted and forecasted ratings. The project publishes the 1.0 specification, usage examples for forecast, real-time, seasonal and temporary ratings, decision records, a conformance suite and a Java client SDK on GitHub.
TROLIE publishes 6 API contracts indexed on the APIs.io network, including Forecasting API, Monitoring Sets API, Seasonal API, and 3 more. Tagged areas include Company, Energy, Electric Grid, Transmission, and Open Standards.
The TROLIE catalog on APIs.io includes 1 JSON-LD context and 2 Spectral governance rulesets.
TROLIE’s developer surface includes changelog, authentication, API reference, getting-started guide, FAQ, engineering blog, support, and 28 more developer resources.
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The Forecasting API operations define the exchange of forecasted ratings, including the 240-hour-ahead forecasted AAR data exchange required by FERC Order 881. The operations su...
[Monitoring Sets](https://trolie.energy/concepts#monitoring-sets) are named sets of power system resources that may be used to filter ratings and limits returned by queries agai...
Seasonal ratings are static ratings associated with extended durations, typically months. These are typically used in both planning and operations. Power system resources that a...
A Seasonal Override instructs the system to use a temporary static rating instead of any concurrent Seasonal Rating for a resource. A typical use case is a so-called 'de-rate' d...
A [Temporary AAR Exception](https://trolie.energy/concepts#temporary-aar-exception) is provided by the Ratings Provider when a Ratings Obligation cannot be fulfilled, due to som...
If permitted by the Clearinghouse Provider, its Ratings Providers can use these functions to exchange real-time ratings, supplementing or replacing traditional telemetry protoco...
Overlays applied on top of this provider's contracts. Each card says who wrote it: a document the provider publishes, or one API Evangelist derived or generated.
aid: trolie
name: TROLIE
description: TROLIE (Transmission Ratings and Operating Limits Information Exchange) is an open-source LF Energy project,
hosted under LF Projects, that defines an OpenAPI-based REST specification for exchanging transmission facility ratings
and operating limits. It responds to FERC Order 881, which requires North American Transmission Owners, Transmission Operators,
Transmission Providers and Reliability Coordinators to exchange ambient-adjusted and forecasted ratings. The project publishes
the 1.0 specification, usage examples for forecast, real-time, seasonal and temporary ratings, decision records, a conformance
suite and a Java client SDK on GitHub.
url: https://raw.githubusercontent.com/api-evangelist/trolie/refs/heads/main/apis.yml
x-type: company
x-source: harvest:spectral-ruleset-github
x-tier: profiled
x-tier-reason: enrichment pass 2026-10-09 (modular-v1; was harvest)
specificationVersion: '0.20'
created: '2026-10-09'
modified: '2026-10-09'
tags:
- Company
- Energy
- Electric Grid
- Transmission
- Open Standards
- OpenAPI
- LF Energy
- Open Source
maintainers:
- FN: Kin Lane
email: kin@apievangelist.com
- FN: APIs.json
email: info@apis.io
image: https://trolie.energy/images/TROLIE-icon-white.svg
common:
- type: AgenticAccess
url: agentic-access/trolie-agentic-access.yml
- type: Spectral
url: rules/trolie-spec-spectral-rules.yml
- type: Spectral
url: rules/trolie-rules.yml
- type: JSONLD
url: json-ld/trolie-context.jsonld
- type: Vocabulary
url: vocabulary/trolie-vocabulary.yml
- type: AgentSkill
url: skills/_index.yml
- type: DataModel
url: data-model/trolie-data-model.yml
- type: ChangeLog
url: changelog/trolie-changelog.yml
- type: Conventions
url: conventions/trolie-conventions.yml
- type: Deprecation
url: lifecycle/trolie-lifecycle.yml
- type: Lifecycle
url: lifecycle/trolie-lifecycle.yml
- type: ErrorCatalog
url: errors/trolie-problem-types.yml
- type: Conformance
url: conformance/trolie-conformance.yml
- type: Overlay
url: overlays/trolie-openapi-overlay.yaml
- type: WellKnown
url: well-known/trolie-well-known.yml
- type: Hosts
url: hosts/trolie-hosts.yml
- type: Vendors
url: vendors/trolie-vendors.yml
- type: SDKs
url: packages/trolie-packages.yml
- type: Packages
url: packages/trolie-packages.yml
- type: Authentication
url: authentication/trolie-authentication.yml
- type: OAuthScopes
url: scopes/trolie-scopes.yml
- type: DomainSecurity
url: security/trolie-domain-security.yml
- type: Website
url: https://trolie.energy/
- type: SpectralRules
url: https://github.com/trolie/spec/blob/39741d03365cb430ab5d7e677312759a7f4a6d14/.spectral.yaml
- type: APIReference
url: https://trolie.energy/spec-1.0
- type: GettingStarted
url: https://trolie.energy/concepts.html
- type: UsageExamples
url: https://trolie.energy/usage-examples.html
- type: FAQ
url: https://trolie.energy/faq.html
- type: Blog
url: https://trolie.energy/community_events.html
- type: GitHubOrganization
url: https://github.com/trolie
- type: GitHubRepository
url: https://github.com/TROLIE/spec
- type: ChangeLog
url: https://github.com/trolie/spec/releases
- type: Issues
url: https://github.com/trolie/spec/issues
- type: Support
url: https://lists.lfenergy.org/g/trolie-general
- type: Foundation
url: https://lfenergy.org/projects/trolie/
apis:
- aid: trolie:trolie-forecasting-api
name: TROLIE Forecasting API
description: 'The Forecasting API operations define the exchange of forecasted ratings,
including the 240-hour-ahead forecasted AAR data exchange required by FERC
Order 881. The operations support submitting rating proposals, querying
in-use limits, and monitoring the health and validity of submissions
against the Rating Provider''s obligations.'
humanURL: https://trolie.energy/spec-1.0
tags:
- Forecasting
properties:
- type: OpenAPI
url: openapi/trolie-forecasting-api-openapi.yml
- type: Documentation
url: https://trolie.energy/spec-1.0
- type: JSONSchema
url: json-schema/trolie-forecast-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-real-time-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-seasonal-ratings-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-realtime-proposal-schema.json
- type: JSONSchema
url: json-schema/trolie-forecast-limits-snapshot-slim-inputs-used-schema.json
- type: JSONSchema
url: json-schema/trolie-realtime-limits-snapshot-slim-inputs-used-schema.json
- aid: trolie:trolie-monitoring-sets-api
name: TROLIE Monitoring Sets API
description: '[Monitoring Sets](https://trolie.energy/concepts#monitoring-sets) are
named sets of power system resources that may be used to filter ratings
and limits returned by queries against these APIs. How Monitoring Sets are
defined is beyond the scope of the TROLIE specification, and it is assumed
that the sender and receiver have predefined the appropriate Monitoring
Sets.'
humanURL: https://trolie.energy/spec-1.0
tags:
- Monitoring Sets
properties:
- type: OpenAPI
url: openapi/trolie-monitoring-sets-api-openapi.yml
- type: Documentation
url: https://trolie.energy/spec-1.0
- type: JSONSchema
url: json-schema/trolie-forecast-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-real-time-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-seasonal-ratings-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-realtime-proposal-schema.json
- type: JSONSchema
url: json-schema/trolie-forecast-limits-snapshot-slim-inputs-used-schema.json
- type: JSONSchema
url: json-schema/trolie-realtime-limits-snapshot-slim-inputs-used-schema.json
- aid: trolie:trolie-seasonal-api
name: TROLIE Seasonal API
description: 'Seasonal ratings are static ratings associated with extended durations,
typically months. These are typically used in both planning and
operations.
Power system resources that are exempt from providing AARs generally
operate at a seasonal rating. Even for resources using dynamic ratings, a
seasonal rating is still necessary. This acts as a recourse when a dynamic
rating is unavailable. For example, a dynamic rating
might be unavailable during communication outages or for forecasts beyond
the ten-day period required by FERC Order 881.'
humanURL: https://trolie.energy/spec-1.0
tags:
- Seasonal
properties:
- type: OpenAPI
url: openapi/trolie-seasonal-api-openapi.yml
- type: Documentation
url: https://trolie.energy/spec-1.0
- type: JSONSchema
url: json-schema/trolie-forecast-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-real-time-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-seasonal-ratings-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-realtime-proposal-schema.json
- type: JSONSchema
url: json-schema/trolie-forecast-limits-snapshot-slim-inputs-used-schema.json
- type: JSONSchema
url: json-schema/trolie-realtime-limits-snapshot-slim-inputs-used-schema.json
- aid: trolie:trolie-seasonal-overrides-api
name: TROLIE Seasonal Overrides API
description: 'A Seasonal Override instructs the system to use a temporary static rating
instead of any concurrent Seasonal Rating for a resource.
A typical use case is a so-called ''de-rate'' due to a temporary clearance
issue for a transmission facility that is exempt from providing AARs.
Exempt facilities typically operate at a seasonal rating. However, instead
of updating the seasonal rating schedule, a Ratings Provider can send a
Seasonal Override.
During the override period, the Clearinghouse uses the Seasonal
Override rating instead of any scheduled seasonal ratings.
For resources required to provide AARs, a Ratings Provider would issue a
Temporary AAR Exception to address temporary conditions requiring a static
rating.'
humanURL: https://trolie.energy/spec-1.0
tags:
- Seasonal Overrides
properties:
- type: OpenAPI
url: openapi/trolie-seasonal-overrides-api-openapi.yml
- type: Documentation
url: https://trolie.energy/spec-1.0
- type: JSONSchema
url: json-schema/trolie-forecast-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-real-time-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-seasonal-ratings-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-realtime-proposal-schema.json
- type: JSONSchema
url: json-schema/trolie-forecast-limits-snapshot-slim-inputs-used-schema.json
- type: JSONSchema
url: json-schema/trolie-realtime-limits-snapshot-slim-inputs-used-schema.json
- aid: trolie:trolie-temporary-aar-exceptions-api
name: TROLIE Temporary AAR Exceptions API
description: "A [Temporary AAR Exception](https://trolie.energy/concepts#temporary-aar-exception) is\nprovided by the Ratings\
\ Provider when a Ratings Obligation cannot be\nfulfilled, due to some temporary operating condition impacting the related\n\
power system resource. This could occur in various scenarios:\n\n * An equipment failure.\n * An unforeseen condition\
\ on a related part of the power grid.\n * Some ambient condition that is not part of the model is heating the\n line,\
\ like a wildfire.\n * Something in the surrounding environment is affecting the amount that a\n line is allowed to\
\ sag. For example, this may occur for lines over\n rivers when very large ships pass under them\n\nA Temporary AAR\
\ Exception serves two main purposes: documenting the reason\nfor the exception and providing a temporary rating value\
\ set. It is employed\nin three distinct circumstances:\n\n1. Firstly, Order 881 mandates documentation and archival of\
\ all use of\n alternate ratings in lieu of AARs. Ratings Providers should continue to\n provide real-time and forecast\
\ ratings for the affected resource, but\n these should match the rating provided with the Temporary AAR Exception\n while\
\ the latter is in effect. This temporary rating, and the reason that\n it occurred, must be captured in history regardless\
\ of the provided\n ratings. The reason and the end date of the effective window may be\n updated after the object has\
\ been created, up to a configurable threshold.\n\n If the Ratings Providers provides ratings that deviate from the\
\ static\n Temporary AAR Exception rating, the Clearinghouse Provider must decide\n whether to use those or the static\
\ rating. The Clearinghouse Provider\n advise its Ratings Providers on how it will choose ahead of time. This\n specification\
\ recommends using the dynamic rating provided, but it does\n not mandate it.\n\n2. Secondly, Temporary AAR Exceptions\
\ apply when the Clearinghouse\n Provider is generating forecast rating proposals on behalf of the Ratings Provider,\
\ e.g., when lookup tables are provided ahead of time by the Ratings Provider.\n Since there is no external ratings,\
\ the Clearinghouse Provider\n wouldn't otherwise know that a temporary static rating is needed. \n\n3. Finally, for\
\ facilities where dynamic ratings are provided, it is\n possible that a communications outage or other issue could prevent\
\ the\n Clearinghouse Provider from receiving the dynamic ratings. In this case,\n the Clearinghouse Provider would\
\ use a Temporary AAR Exception rating."
humanURL: https://trolie.energy/spec-1.0
tags:
- Temporary AAR Exceptions
properties:
- type: OpenAPI
url: openapi/trolie-temporary-aar-exceptions-api-openapi.yml
- type: Documentation
url: https://trolie.energy/spec-1.0
- type: JSONSchema
url: json-schema/trolie-forecast-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-real-time-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-seasonal-ratings-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-realtime-proposal-schema.json
- type: JSONSchema
url: json-schema/trolie-forecast-limits-snapshot-slim-inputs-used-schema.json
- type: JSONSchema
url: json-schema/trolie-realtime-limits-snapshot-slim-inputs-used-schema.json
- aid: trolie:trolie-realtime-api
name: TROLIE Realtime API
description: 'If permitted by the Clearinghouse Provider, its Ratings Providers can use
these functions to exchange real-time ratings, supplementing or replacing
traditional telemetry protocols like ICCP.'
humanURL: https://trolie.energy/spec-1.0
tags:
- Realtime
properties:
- type: OpenAPI
url: openapi/trolie-realtime-api-openapi.yml
- type: Documentation
url: https://trolie.energy/spec-1.0
- type: JSONSchema
url: json-schema/trolie-forecast-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-real-time-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-seasonal-ratings-proposal-status-schema.json
- type: JSONSchema
url: json-schema/trolie-realtime-proposal-schema.json
- type: JSONSchema
url: json-schema/trolie-forecast-limits-snapshot-slim-inputs-used-schema.json
- type: JSONSchema
url: json-schema/trolie-realtime-limits-snapshot-slim-inputs-used-schema.json
x-enrichment:
date: '2026-10-09'
status: enriched
artifacts_added: 43
pass: modular-v1
engine: identity=anthropic,contract=anthropic,surfaces=anthropic,docs=anthropic,regulatory=anthropic
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